# How would you write the equation of the electron affinity of S-?

Oct 28, 2015

Electron affinity is known as an atom's love for electrons. It is the tendency to acquire an electron.

From the perspective of the atom, it acquires energy from the electron so that it can be absorbed into the atom, and thus, electron affinity is conventionally written to be positive. When the electron is more easily absorbed, the electron affinity is less positive.

When energy is absorbed from the electron as potential energy, the kinetic energy of the electron is released. You would write a reaction that therefore involves the absorption of an electron into the atom and the release of energy from the electron.

1. "S" + e^(-) -> cancel("S"^(-)) + E_(e^(-),1)
2. cancel("S"^(-)) + e^(-) -> "S"^(2-) + E_(e^(-),2)
$- - - - - - -$
${\text{Overall": " S" + 2e^(-) -> "S}}^{2 -} + {E}_{{e}^{-} , 1} + {E}_{{e}^{-} , 2}$

In contrast, ionization energy is the tendency to give up an electron.

From the perspective of the atom, it supplies energy to the electron as it is being released from the atom, and so ionization energy is conventionally written to be negative. When the electron is more easily released, the ionization energy is less negative.

When energy is released from the electron as kinetic energy, potential energy is stored in the atom. You would write a reaction that therefore involves the release of an electron from the atom and the absorption of energy into the atom.

1. "S"^(2-) + E_(e^(-),1) -> cancel("S"^(-)) + e^(-)
2. cancel("S"^(-)) + E_(e^(-),2) -> "S" + e^(-)
$- - - - - - -$
$\text{Overall": " S"^(2-) + E_(e^(-),1) + E_(e^(-),2) -> "S} + 2 {e}^{-}$